Humans. We kill each other animals and pollute the environment.
Mosquito, it causes malaria which kills over 10,00 humans, cattle and other mammals a year
The worlds most lethal animal is the funnel web spider who lives (of course) in Australia
I think the most graceful animal is probably a Swan because they're good-natured and caring.
the chimp is the smartest animal because the somehow reminds people of other people.